Algae World: Sellaphora

Blackford Pond

Blackford Pond

Blackford Pond is crescent-shaped
and lies in a small public
park, surrounded by planted rhododendrons, deciduous trees and shrubs,
and
conifers. There is a path along the whole of the north-western side of
the pond, but the eastern side is almost inaccessible. There is a small
island
near the centre. The pond is not natural but was created in
the
nineteenth century, as the city expanded. On the east side, the pond is
flanked by the crags of Blackford Hill, while to the SW there are
garden allotments, which probably add considerably to the nutrient
loading of the pond, which fills by groundwater seepage. There is no
visible inflow and a drain at the north-east end keeps the
level stable, except in the wettest weather. In the 1980s, the
pond regularly froze in winter, at least around its
margins, but a
covering of ice
is now very unusual. The pond is generally home to many tens
of
ducks, geese, swans and gulls, fed by oversentimental children and
grandparents. It used to be used by the University of Edinburgh
ecologists for demonstrations of the mark-recapture method for
assessing the size of fish populations.

These views were taken in the 1980s, before the Parks
Department of the City Council made significant alterations to the pond
and its perimeter. The top photograph shows the pond from the SW
end, a view now obscured by shrubs and reeds (Phragmites). The
principal sampling site David Mann used (throughout the 1980s
and subsequently, apart from a brief period in 1980-1982) is
at this end, 3-15 m offshore, in 30-60 cm water depth. The sediment
here is very fine and organic and highly reduced (black) except at the
surface. The lower photograph was taken from Blackford Hill.